Thermoplastic fibre, hybrid yarn, fibre perform and method for producing fibre performs for fibre composite components, in particular high performance fibre composite component, using the same, fibre composite component and method for producing fibre composite components, in particular high performance fibre composite components

ABSTRACT

A thermoplastic fiber comprises a core constructed of a first material, a shell positioned to surround the core and constructed of a second material, and magnetic particles that are ferromagnetic and/or ferrimagnetic particles where the particles are either mainly, almost exclusively, or exclusively arranged in the shell. A fiber perform or semifinished textile product includes at least one thermoplastic fiber. A hybrid yarn comprises reinforcement fibers, thermoplastic fibers, and at least some of the plurality of thermoplastic fibers include at least proportionately ferromagnetic and/or ferrimagnetic particles.

PRIORITY

This application is a Continuation in Part of International ApplicationPCT/DE2011/001984 filed Nov. 14, 2011, which takes priority from GermanPatent Application DE 10 2010 052 078.0 filed Nov. 18, 2010, thecontents of both prior applications being incorporated herein byreference. This application also takes priority from U.S. ProvisionalPatent Application 61/613,541 filed Mar. 21, 2012, the contents of whichare also incorporated herein by reference.

BACKGROUND

The present invention relates to a thermoplastic fiber, a hybrid yarn,in particular suitable for thermal fixing of fiber preforms for,preferably endless fiber reinforced, fiber composite components, inparticular high performance fiber composite components, a fiber preformand a method for producing fiber preforms for, preferably endless fiberreinforced, fiber composite components, in particular high performancefiber composite components, a fiber composite component and a method forproducing, preferably endless fiber reinforced, fiber compositecomponents, in particular high performance fiber composite components.The fiber preform is a product or semi-finished product which isconstructed from fibers. The carrying layer can consist for example of atool, a film, a fiber structure or a laminate. High performance fibercomposite components are fiber composite components with particularlygood thermal and mechanical properties.

Throughout the fields of traffic engineering, aeronautical, andaerospace engineering, in the fields of mechanical engineering, and inthe field of sports, there are increasingly requirements for lightweightconstruction solutions. Where masses are moved, lightweight constructionis an efficient method in order to increase the performance capacity ofthe product and to simultaneously reduce the required energy inoperation and thus the running costs. Carbon fiber reinforced plasticshave a high lightweight construction potential as they have a highspecific strength and rigidity with a low density. The use of structuresmade of carbon fiber reinforced plastics on a large scale frequentlyfails, however, due to its production and material costs. In order to beable to produce components from this material at competitive costs theproduction process must be extensively automated and have a low cycletime. Furthermore the material costs must be minimised and allmechanical, thermal and chemical requirements thereby fulfilled.

Thermoplastic matrices have advantages over duroplastics. They can bemaintained at room temperature without limitation, no dissolvents mustbe used during processing, the cycle times are shorter, the materialsare weldable and more tolerant to loads than duromers due to a higherviscosity. Endless carbon fibers in thermoplastic matrices are processedtoday in fabric form to so-called organo sheets. The production processcomprises a plurality of work steps. Firstly (0°/90°) fabrics must beproduced. The sizing agent necessary for the web process to protect thefibers is removed before impregnation with the melted thermoplasticsthrough a wet chemical process. Subsequently the dried fabrics areimpregnated with the thermoplastic melt or via the film stacking method.The matrix has a very high viscosity of 10³ to 10⁵ Pa·s (water 1 mPa·sat 20° C.). In order to ensure a good impregnation of all fibers, aftersoaking the individual fabrics are constructed to form laminates andconsolidated by means of a double belt or interval hot press. Thelaminates of the organo sheets can be constructed up to a thickness of10 mm and be processed in a reshaping process to form components.

Disadvantages in this process are the high-resource manufacturingprocess and the expensive starting materials. For this reason the fieldof application has to date been predominantly limited to individualcomponent groups in aviation.

In comparison with organo sheets, a shorter production chain can beachieved by using hybrid yarns and textiles. In order to ensure shortflow paths and an associated rapid impregnation of the reinforcementfibers with the thermoplastic matrix the matrix must be brought as closeas possible to the filaments. Hybrid textile structures which areequipped, besides the endless reinforcement fibers for example ofcarbon, with a thermoplastic component for consolidation can be easilyprocessed to form fiber composite components. In case of comminglinghybrid yarns both components are mixed well in the yarn cross-section sothat the flow paths for filament wetting are minimised during theconsolidation phase. Disadvantages are, however, slight filament damageand orientation deviations within the yarn. The carbon filaments areswirled together with the thermoplastic filaments for example throughair jets and do not subsequently lie—as in a roving—parallel to eachother and thus result in a reduction in the possible componentrigidities and strengths.

For the load-optimised design and maximum substance exploitation it is aprecondition that the particular advantages in terms of properties ofthe fiber composite materials fully take effect.

The tailored fiber placement (TFP) method offers great potential for anefficient production of load-optimised designed components from fibercomposite materials. In TFP technology reinforcement fibers arecontinuously laid up in textile preforms corresponding to the stressdirections. A virtually ideal textile reinforcement structure is thusfacilitated. A stitching machine positions and fixes the fiberscorresponding to the force flow and stress analyses on a stitching base(carrying layer). Through coordinated lay-up of a plurality ofstitched-on preforms a semi-finished product for a multi-axis loadablecomponent can be subsequently produced. The process is highly automatedand facilitates a high productivity as a plurality of stitching headsare arranged beside one another which can simultaneously work on acommon stitching base.

Disadvantages are filament damage through the stitching process, fiberundulations and resin nests which arise through the penetration ofstitching threads. In addition there are limitations in the maximumnumber of layers of a TFP preform. The further processing to a componentfrequently takes place in staff-intensive and time-intensive resininjection or resin infusion methods so that current applications arelimited to components with low numbers of parts.

Conventional tow placement systems, as offered for example by Cincinnatiand Coriolis Composites, use in particular pre-impregnated fibers orfiber bands. These can be based upon thermoplastic or duromer matrixsystems. Repetition precision in the manner of +/−0.3 mm can beachieved. For sufficient adhesion of the fibers pressure forces of 100 Nto 1500 N are necessary depending upon the matrix. A robot-guided lay-uphead creates, with a ¼″ wide yarn, a lay-up output of approximately 18kg/h. Higher lay-up rates can be achieved through a parallelisation.

Investigations into curved lay-up paths have shown, however, that incase of in-plane radii of approximately 1.5 m already clear fiberwaviness arises. Load-optimised fiber orientations for complex stresspatterns, as used in TFP methods, cannot be realised with thistechnology. The reason for this is the high rigidity of the fiber bandwhich does not facilitate a displacement of the filaments relative toeach other, in comparison with commingled hybrid yarns.

In general shell/core bi-component fibers are used today in the clothingand furniture industry, filter technology and medical technology. Theshell/core ratio can hereby lie between 1/99 and 50/50 depending uponthe application. The use of bi-component fibers as binding fibers hasalready been tried and tested in non-woven fabric production. Shellcomponents are used here which have a lower melting point than the corecomponents and can thus be directly thermally activated. This cannot berealised for thermally stressed components, as the fiber shell alsocontributes to the later matrix of the fiber composite component.

It thus remains to be stated that, in spite of the high technicalpotential of the fiber-reinforced thermoplastics, it has not beenpossible to use these to date for many applications due to the expensiveand high-resource production process. When using organo sheets there isfrequently 30% production waste and more. The textile fiber structuresoften lead to reduced rigidities and strengths in the component asproduction-related fiber damage and undulations arise in the web orstitching process. Existing tow placement methods are based uponexpensive semi-finished products, with which only large in-plane radiican be realised. The lightweight construction potential for componentswith complex stress patterns is therefore only insufficiently exploited.

German Document DE 10 2007 009 124 A1 discloses an induction-supportedproduction method and a production device for moulded elements of fibercomposite materials. The method comprises the lay-up of a band-formmaterial in a moulding element. Said band-form material contains bothreinforcement fibers and also thermoplastic or duroplastic resin. Theresin is provided with magnetic particles which lead, upon lay-up, toheating of the band-form material through magnetic induction heating.The magnetic particles are distributed homogeneously in the resin, sothat upon lay-up the whole resin is melted and the band-form material isalready brought into the three-dimensional end form. A high proportionof the magnetic additive, relatively large lay-up radii and a limiteddegree of automation in mass production are associated with this.

SUMMARY

It is thus an object of the invention to facilitate an extensivelyautomated, material-saving and thus economical production of fibercomposite components. This object is achieved with a thermoplasticfiber. The heating rate will be particularly advantageous if there is ahigh proportion or total share of the particles in the shell and only asmall proportion or zero share in the core. This object is furtherachieved with a hybrid yarn, in particular suited for thermal fixing offiber preforms for, preferably endless fiber reinforced, fiber compositecomponents, in particular high performance fiber composite components,comprising a plurality of preferably round reinforcement fibers and aplurality of preferably round thermoplastic fibers, wherein at leastsome of the plurality of thermoplastic fibers include at leastproportionately ferromagnetic and/or ferrimagnetic particles, preferablyin the nanometre range. The nanometre range relates to the individual orprimary particles.

The present invention also provides a fiber preform and a method forproducing fiber preforms. The fiber preform or the semifinished textileproduct is at least partially built up by the hybrid yarn and/or thethermoplastic fiber. Further, the invention provides a nonwoven fabric,non-crimp fabric, multiaxial multiply fabric, winding form, wovenfabric, knitted fabric or braided fabric. In addition the inventionprovides a fiber composite compound according to claim 32 and a methodfor producing the same.

According to one contemplated embodiment of the invention, thethermoplastic fiber includes a first material and a second material thatare identical. It is further contemplated that in some embodiments thefirst material and the second material can be different. This can beparticularly advantageous for filters etc.

In some contemplated embodiments, the diameter of the individualparticles is in a range of about 10 nm to about 20 nm and in someembodiments preferably about 13 nm. In one anticipated embodiment, thediameter of agglomerates of the particles is in a range of about 100 nmto about 200 nm and preferably about 150 nm.

Conveniently, the thermoplastic fiber comprises or consists ofpolyetherketone, in particular polyetheretherketone (PEEK),polyphenylene sulphide (PPS), polymide, in particular polyetherimide(PEI), or polysulfone (PSU), in particular polyethersulfone (PES). Saidthermoplast can be considered as high performance thermoplast. Thepolymer Vestakeep 2000 G seems to be particularly suitable.

In some embodiments the thermoplastic fiber are unstretched. Someembodiments further contemplate the particles are iron oxide modified.

In some embodiments, the diameter of the core may be in a range of about5 μm to about 60 μm and/or the thickness of the shell may be in a rangeof about 0.1 μm to about 20 μm. In further contemplated embodiments, theconcentration of the particles in the shell is in a range of about 10weight percent to about 50 weight percent. It is further contemplatedthat the viscosity of the thermoplastic fiber can be in a range of about100 to 1000 Pa·s.

Some contemplated embodiments included providing with the hybrid yarnthat the thermoplastic fibers respectively include a core, whichincludes or consists of a first material, and a shell surrounding thecore, which includes or consists of a second material. Thecore-shell-structure is particularly advantageous.

The invention also contemplates that the first material and the secondmaterial can be identical. Alternatively, the first and the secondmaterial can be different. And it is further contemplated that theparticles can be advantageously arranged mainly, almost exclusively orexclusively in the shell.

According to one anticipated embodiment, the diameter of the individualparticles can be in a range of about 10 nm to about 20 nm and preferablyabout 13 nm. Additionally, the diameter of agglomerates of the particlesmay be in a range of about 100 nm to about 200 nm and preferably isabout 150 nm.

In some contemplated embodiments, the reinforcement fibers can usefullycomprise or consist of anorganic fibers, in particular carbon or glass,or synthetic polymers, in particular aramid. The thermoplastic fiberscan advantageously comprise polyetherketone, in particularpolyetheretherketone (PEEK), polyphenylene sulphide (PPS), polyimide, inparticular polyetherimide (PEI) or polysulfone (PSU), in particularpolyethersulfone (PES) or consist thereof. In such embodiments, thethermoplastic fibers can be advantageously unstretched. Additionally,the particles can be usefully iron oxide modified such that theparticles are modified iron oxide particles. The modification comprisesparticles having a core/shell structure, the core comprising at leastone iron oxide selected from Fe₂O₃ and Fe₃O₄. The shell comprises orconsists of amorphous silica and usually displays a thickness of theshell is 5-20 nm. The shell improves the compatibility of the particleswith the thermoplastic material, to make it easier for it to be able todisperse uniformly in the thermoplastic material.

In a particular embodiment of the invention, the BET surface area of theparticles is 10-70 m²/g. The best results when used for conductiveheating are obtained with particles having a BET surface area of 15-25m²/g. The particles may be in form of isolated primary particles oraggregates. The primary particles are substantially pore-free, but havefree hydroxyl groups on the surface and may have different degrees ofaggregation. The aggregates are three-dimensional aggregates. Ingeneral, the aggregate diameter, in one three-dimensional direction ineach case, is preferably not more than 250 nm, generally from 30-200 nm.Several aggregates may combine to form agglomerates. These agglomeratescan be separated again easily. In contrast, the division of theaggregates into the primary particles is generally impossible.

The content of iron oxide is 50-90% by weight, preferably 75-85% byweight, calculated as Fe₂O₃ based on the core/shell particle.

The core of the particles preferably comprises the iron oxideshaematite, magnetite and maghemite. The proportion of haematitedetermined from the X-ray diffractograms preferably is 20-30 by weight,that of magnetite 30-60% by weight, and that of maghemite 40-50% byweight, where the proportions add up to 100% by weight.

According to one contemplated embodiment of the invention, thereinforcement fibers and the thermoplastic fibers are homogeneouslymixed. The diameter of the reinforcement fibers can also be in a rangeof about 5 μm to about 15 μm. For example the range of diameters ofreinforcement fibers is about 5 μm to about 11 μm for carbon, about 5 μmto about 13 μm for glass and about 10 μm to about 15 μm for aramid andbasalt.

In some contemplated embodiments, the fiber volume content of thereinforcement fibers within the hybrid yarn is in a range of about 50volume percent to about 70 volume percent. For example in the aviationsector fiber volume contents of 50 volume percent, regarding compositeswith thermoplastic matrix, are often required.

In some embodiments, the fiber preform or semifinished textile productcan be produced by using the TFP and/or Tow Placement Technology.

The invention also contemplates that in the method for producing fiberpreforms, the hybrid yarn can be pressed during or after lay-up onto thecarrying layer.

In a preferred embodiment of the fiber composite component, theconcentration of the particles is in a range of about 0.01 volumepercent to about 20 volume percent, and more preferred of about 0.01volume percent to about 2 volume percent.

The invention is based upon the surprising recognition that through thespecial design of the thermoplastic fiber and of the hybrid yarns, aresource-efficient process chain can be realised for the production ofthe thermoplastic fiber and of high performance fiber compositecomponents even for complex geometries.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention follow from theattached claims and the following description, in which a plurality ofexemplary embodiments are individually explained by reference to theschematic drawings, in which:

FIGS. 1 to 3 show cross-sectional views of individual thermoplasticfibers of a hybrid yarn according to particular embodiments of theinvention;

FIGS. 4 to 6 show cross-sectional views of a plurality of thermoplasticfibers comprising one or more of the thermoplastic fiber types of hybridyarn, shown in FIGS. 1 to 3, according to particular embodiments of theinvention;

FIGS. 7 and 8 show cross-sectional views of hybrid yarns according toparticular embodiments of the invention;

FIGS. 9 and 10 show a side view and a top view to illustrate a methodfor producing fiber preforms according to particular embodiments of theinvention;

FIG. 11 shows an example of a process chain for CFRTP (Carbon FiberReinforced Thermoplastic)-Parts made by hybrid performs;

FIG. 12 shows hybrid TFP-preforms for a hatrack bracket with theside-by-side principle (left) and FEA of CFRP-Part with Tsai-Wu failurecriteria (right);

FIG. 13 shows hybrid TFP-preforms for thermoplastic window frame madefrom commingled yarns (left) with detail (right);

FIG. 14 shows polished cut image of unidirectional laminates made of Nm3.2 TPFL CARBON/PPS, Schappe Techniques commingling yarn (left) andTICONA® PPS-Fortron 032000 SF3001/Tenax®—E HTS40×011 12K 800texside-by-side (right);

FIG. 15 shows a comparison of tensile properties of laminates made fromhybrid preform and commercial CFRTP-Laminates made from woven fabrics;

FIG. 16 shows the influence of MagSilica® VP300 on Vestakeep 2000 Gviscosity;

FIG. 17 shows core/shell filaments; and

FIG. 18 shows the heat up behaviour of different test specimen.

DETAILED DESCRIPTION

FIG. 1 shows a thermoplastic fiber 10 which does not contain anyferromagnetic and/or ferrimagnetic particles, while the thermoplasticfiber shown in FIG. 2 comprises a core 12 and a shell 14 surrounding thecore, wherein the core 12 and the shell 14 ideally consist of the samematerial, apart from the fact that the shell 14 is additionallyprovided, preferably evenly, with ferromagnetic particles, of which onlya few are identified by the reference numeral 16.

The thermoplastic fiber 10 shown in FIG. 3 is evenly provided withferromagnetic particles, of which only a few are identified by thereference numeral 16. Although the ferromagnetic particles are shownspherically in FIGS. 2 and 3 it will be appreciated that they can alsohave other forms.

FIG. 4 shows a multitude of thermoplastic fibers 10 as a mixture of thethermoplastic fiber types shown in FIGS. 1 and 3, whereby merely some ofthe thermoplastic fibers are identified. The size ratios serve only forbetter illustration. Uniform diameters are ideal for homogeneous mixing.

FIG. 5 shows a plurality of thermoplastic fibers 10 of the type shown inFIG. 2. The final result is the mixture shown in FIG. 6 of thethermoplastic fiber types shown in FIGS. 1 and 2, whereby only a fewthermoplastic fibers are identified by the reference numeral 10. Themixture shown in FIG. 6 comprises a minimum particle proportion (minimumor better reduced nano-particle concentration: in the hybrid yarn,non-modified and shell-modified thermoplastic fibers are present)(maximum or better high nano-particle concentrations: all thermoplasticfibers are evenly modified over the thermoplastic fiber cross-section).

FIG. 7 shows a hybrid yarn 18 made of thermoplastic fibers 10 of thetype shown in FIG. 3 and also reinforcement fibers 20, of which only afew are identified.

The hybrid yarn shown in FIG. 8 consists in principle of the pluralityof thermoplastic fibers shown in FIG. 6, of which only a few areidentified by the reference numeral 10, and of reinforcement fibers 20,of which likewise only a few are identified.

FIGS. 9 and 10 show how a hybrid yarn 18 according to a particularembodiment of the invention, which is wound on a coil 22, is unwoundfrom it and passed through a magnetic induction heating device in theform of an induction coil 24 and subsequently laid up by means of apressure roller 26, which is optionally cooled, on a carrying layer 28and pressed thereon. The laid up hybrid yarn sticking to the carryinglayer is supposed to be identified by the reference numeral 30. FIG. 10shows the path curve with a lay-up ratio r in the magnitude ofapproximately 20 mm as far as infinite.

In one contemplated embodiment of the invention, the hybrid yarns 18 areproduced from functionalised, that is to say shell-selectivelyinductively meltable shell 14—core 12 thermoplastics 10, preferablypolyetheretherketone (PEEK) and reinforcement fibers 20, preferablycarbon fibers. In order to produce a fiber preform by means of thepreviously described modified TFP method, the shell 14 of thethermoplastic fibers 10, modified with ferromagnetic particles 16,preferably iron oxides such as MagSilica®, is inductively activated andmelts. During the pre-fixing the melted shell component hereby acts as abinding agent. In contrast with the normal TFP method with a stitchinghead, the use of stitching threads can hereby be omitted, whichotherwise leads to filament damage, fiber undulations and resin nests.Furthermore with this method there is no limitation of the number oflayers as the layers are stuck one on top of the other and do not needto be stitched.

The high flexibility of the hybrid yarn further facilitates very smalllay-up radii and is thus superior to the tow placement method withcomplex component geometries.

On the basis of the preliminary investigations for the shell-coredistribution within the bi-component thermoplastic fibers, a shellvolume portion of 10% by volume could be technically realised. In termsof large scale, lower shell portions in the region of 1% can be achievedso that the required portion of ferromagnetic particles in the componentcan lie below 1%.

A first example of a process chain for manufacturing endless fiberreinforced fiber composite components out of hybrid yarn will now bedescribed. It can be divided into the following sub-steps:

Hybrid Yarn Production

In a bi-component melting-spinning process the same thermoplastic isused for the shell and also for the core of the thermoplastic fiber. Theshell is hereby modified with ferromagnetic particles. By means of forexample the commingling method, modified air texturing machines orfriction spinning, the shell-core thermoplastic fibers and thereinforcement fibers can be homogeneously mixed to a hybrid yarn in aratio which corresponds to the later fiber volume content of the fibercomposite component. The fiber finenesses are orientated to the hybridyarn homogeneity and the resulting fiber composite componenthomogeneity.

Preforming Tow Placement

A lay-up head (not shown) provided with magnetic induction heatingtechnology thermally activates the shell of the thermoplastic fibers viathe ferromagnetic particles so that the hybrid yarn can be laid up andfixed in accordance with force flow on a 2D development of a componentend contour (carrying layer). Undulations of the reinforcement fibersand limitations in the number of layers can be avoided in this method incomparison with normal TFP technology.

The lay-up head can be installed both on a robotic arm and on a portalsystem. It is also possible with the described lay-up technology to layup different hybrid yarns on any two-dimensional paths. The fiberarchitecture can thus be optimally adapted to the later fiber compositecomponent load in order to thus fully exploit the material potential.Through lay-up on the end contour all the material used is used in thefiber composite component. Through this efficient use of material, inspite of expensive starting materials, high performance fiber compositecomponents can be produced at favourable prices. This technology of alay-up head can also be transferred to other methods, such as formexample the winding method.

Consolidation

The three-dimensional forming and consolidation can subsequently takeplace in a thermoforming process.

The installation technology can be adapted well. This offers freedom inthe component geometry which can be produced. In addition, the method issuitable—due to the low refitting resources—also for small scaleproduction. The semi-finished products are product-non-specific and canthus be used for a very broad spectrum of applications.

The good adaptability of the installation technology to differentgeometries also opens up opportunities for economic production ofvariant-rich series in mechanical engineering and in orthopaedictechnology. The fiber composite components are constructed from simpleand specific semi-finished products and have a low waste. They are endcontour precise, can be thermally joined to injection moulded parts anddo not require any corrosion protection.

An overview of another example of a process chain is given in FIG. 11for a frame structure. Feedstock, either a plied side-by-side (FIG. 11)or a commingled yarn is a combination of carbon fiber with thermoplasticmultifilaments. For the side-by-side version the matrix filaments(PA6—Ultramid B27 03, BASF; PPS—Fortron 0320CO SF3001, Ticona;PEEK—Vestakeep 2000, Evonik) are produced on a melt spinning plant fortechnical multifilaments (F. Fourné) with a low degree of shrinkage andwithout sizing for a better fiber matrix adhesion. The correspondingcarbon fibers were Tenax®-E HTS40 X011 12K 800tex.

Preforms are produced on a TFP facility (Tajima TMLH-G108 Type D3-1)with a modified stitching head on a PVAL foil (Solublon, Typ KA 30micron) as substrate.

Fiber lay-up with TFP-technology allows manufacturing of textilepreforms with several layers in one step. Each hybrid yarn (plied orcommingled) is fixed with an upper and a lower thread by zigzagstitches. Except for the substrate a one layer preform is nearlysymmetrical. Additional TFP-layers demand further upper and lowerstitching thread, so that TFP-preforms have on the lower side aconcentration of stitching thread. Furthermore the lower layers are muchmore transfixed than the upper ones. To avoid matrix agglomerations(build-up of lower stitching thread) and filament damage the matrix willbe modified with ferromagnetic particles (MagSilica® Evonik), in which asingle particle has a nano scale. First estimations suggest that a nanoparticle concentration less than 1 weight percent, corresponding to thetotal CFRTP-part weight, will be enough to reach an economical preformproduction process.

The subsequent drapery and consolidation takes place in a Rucks KV 214press. Here the melted stitching thread and the thermoplasticmultifilament results in the matrix fraction. Basic parameters for theconsolidation process are given by Schappe Techniques (“N.N.: ENSEMBLEFiches BDEF GB Issue 03-2009, Schappe Techniques, 2009”) for acommercial commingled yarn (Nm 3.2 TPFL CARBON/PPS, Schappe Techniques).Moulding and demoulding temperature was 200° C. and consolidationtemperature was 315° C. The realised heat-up and cooling-down speed waslimited by the equipment to 10 K/min. Before testing a past-conditioningwas made at 230° C.

Closing the material performance was characterised by polished cut imageanalysis and mechanical testing according to DIN EN 2561 (test apparatusZwick/Roell Z250).

Hybrid-Preforming

Different geometries of hybrid preforms have been realised. Thegeometrical flexibility of the TFP-Process is demonstrated in the shapeof a hatrack bracket (FIG. 12; Hybrid TFP-Preforms for a hat trackbracket with the side-by-side principle (left) and FEA of CFRP-Part withTsai-Wu failure criteria (right) (“Shi, Y.: Beitrag zurProzesskettenentwicklung von endlosfaserverstärkten Thermoplastbauteilenfür Groβserien, Diploma Thesis, Universität Bremen, 22.07.2009 Bremen”))with the side-by-side principle and a window frame (FIG. 13; HybridTFP-Preforms for thermoplastic window frame made from commingled yarns(left) with detail (right)) for aircraft applications with commingledyarns. In general this process is preferred for reinforcing loadapplication regions and highly stressed structures.

Standard textiles like woven or knitted fabrics would have for thisgeometry more than 50% cutting scrap and a much lower performance fromthe mechanical point of view. The use of dry carbon fiber multifilamentyarns enabled us fiber lay-up on small radii down to 10 mm without anyvisible filament undulations causes by the fiber path.

Because of the complex stress fields of load application areas, acombination of the consolidated CFRTP-part with injection die mouldingis useful for this part. Finite element analyse shows that thiscombination enhanced the ultimate load by about 30% while adding 15%weight of CFRTP (“Shi, Y.: Beitrag zur Prozesskettenentwicklung vonendlosfaserverstärkten Thermoplastbauteilen für Groβserien, DiplomaThesis, Universität Bremen, 22.07.2009 Bremen”).

The preform in the photo in FIG. 13 consists of 3 layers with differentply arrangement geared to a polar coordinate system. Both principles ofhybrid TFP-preforms are characterised by a good repeatability due to thehigh degree of automation.

Consolidation

The internal laminate-structure of hybrid preforms made from commingledyarns as well as the ones which were created in side-by-side technologyis regular. Polished cut images of laminates made from commingled yarnsfrom Schappe Techniques are characterised by resin rich areas (FIG. 14;Polished cut image of unidirectional laminates made of Nm 3.2 TPFLCARBON/PPS, Schappe Techniques commingling yarn (left)). Thereinforcement fibers appear in fiber bundles. Polished cut image oflaminates made from hybrid side-by-side preforms show a more homogeneousfiber allocation (FIG. 14; TICONA® PPS-Fortron 0320CO SF3001/Tenax®-EHTS40 X011 12K 800tex side-by-side (right)).

In both cases the laminates are fully impregnated and no phaseseparation is visible. The stitching thread is completely melted and hasbecome a part of the matrix. The realised fiber volume content is about45%.

Mechanical Properties

FIG. 15 (Comparison of tensile properties of laminates made from hybridperform and commercial CFRTP-Laminates made from woven fabrics (*allvalues are related to a total fiber volume content of 50%)) is showingthe determined tensile properties of produced PA6 laminates made fromside-by-side hybrid preforms and PPS laminates made from commingledyarns compared with properties of commercial CFRTP-laminates (“N.N.:Mechanical Data for Carbon CD0286/PPS, TenCate, 2006”) for the aircraftindustry. For easy comparison with the commercial woven 0°/90°-laminates(fiber volume content of 50%) the values of the test laminates arescaled up to the identical fiber volume content.

Actually, the realised mechanical properties are higher for theside-by-side laminate than for the commercial ones due to the morestretched fibers without woven undulations. For the commingled yarnespecially the tensile modulus is lower due to fiber breakages caused bythe commingling process.

Depending on later applications the used hybrid yarn can consist ofdifferent types of reinforcing fibers (carbon, glass, basalt, aramid)and any type of thermoplastic resin. Preferable are high performancethermoplastic resins like Vestskeep 2000 G (PEEK, Evonik). The hybridyarn build-up can be side-by-side, commingled or wrapped, in which thereinforcing fiber volume content can be designed regarding the laterapplication (e.g. aircraft industry 50%).

For the preliminary induction analyses modified matrix filaments areproduced with a spinning tester in vertical direction (SDLAtlas—Laboratory Mixing Extruder). The corresponding PEEK compounds weredelivered by Evonik with a MagSilica® 50-85 (content of 10 weight-%) andMagSilica® VP300 (content of 15, 20 and 30 weight-%). MagSilica VP300 isparticularly advantageous for heating. The spun filaments arecharacterized by polished cut image analysis, scanning electronmicroscopy (SEM) and mechanical single fiber testing according to DIN ENISO 5079: 1996 (Dia-Ston equipment). Afterwards the heat up behavior isanalyzed using a Himmelwerk Sinus 52 ring coil (inner diameter: 6 mm,length: 22 mm, power: 6.0 kW; frequency: 1.8 MHz) and contactlesstemperature measurement.

Filament Spinning

The effect of Vestakeep 2000 G modification through MagSilica® 300VP isshown in FIG. 16 (Influence of MagSilica® VP300 on Vestakeep 2000 G). Ascan be seen from the graph the complex viscosity decreases whenMagSilica® is added to the polymer. Overall the viscosity is in thepreferable region (100-1000 Pa·s) for the melt spinning process. In thisviscosity region the fiber formation shows normally the best performanceand the process stability is increased.

The filament spinning takes place at 360° C. In contrast to pure PEEKthe spinning temperature has to be lowered for a good fiber formationdue to the lower viscosity. The lower spinning temperature results inhigher melt stiffness but otherwise the nano particles induce meltfracture. However spin drafts up to 100 could be reached in thelaboratory scale. In comparison to typical spin drafts for melt spunfibers (F. Fourné, “Synthetische Fasern—Herstellung, Maschinen undApparate, Eigenschaften”; Handbuch für Anlagenplanung,Maschinenkonstruktion und Betrieb; Hanser Verlag, München/Wien, 1995,Chapt. 3, p. 182”) this is promising regarding the industrialimplementation.

If the higher spinning speeds in industrial scale cause unexpectedfilament breakages the core/shell filament build up could be used,whereas a non modified pure PEEK core acts as a spinning carrier (FIG.17; Core/shell filaments). With this type of filament a non fiberforming thermoplastic resin can also be used as shell component.

The core/shell structure generates also more advantages for which reasonthis filament structure is preferred.

-   -   1. During the bonding the unmodified core stabilized the melted        shell, whereby faster perform production rates can be used.    -   2. To reach high heating rates the MagSilica® content of the        shell can be chosen very high, whereas the unmodified core makes        sure that the overall concentration is still low. The        feasibility through the spinning carrier effect is ensured.    -   3. Through changing the thickness the adhesion strength can be        controlled. Normal industrial shell fraction can be from 1-99        vol.-%.    -   4. Depending on the application different materials can be used        for the core and shell component. It is not necessary that core        and shell have the same polymeric feedstock.    -   5. Overall this technology can generate CFRP-parts with a very        low amount of nano particles:        -   30 wt-% MagSilica® in the shell corresponds to 11 vol-%.            With 10% shell fraction and 50% modified binding matrix            filaments this leads to 0.3 vol-% nano particles for an            aircraft component with a fiber volume content of 50%.

Filament Properties

With 90-100 MPa for the tensile strength, complete nano modified PEEKfilaments are comparable to neat PEEK according to DIN EN ISO 527-2.These mechanical properties (for unstretched filaments) are sufficientfor a safe handling during the modified TFP process. Depending on theprocess parameters filament diameters can be realized between 10 and 100μm.

Heat Up Behavior

Heating up experiments showed that with MagSilica® VP300 higher heatingrates can be generated in comparison to MagSilica® 50-85. Therefore thefollowing results concentrate on VP300.

A big advantage of using filament is the possibility of using highperformance induction coils. These coils are very compact with innerdiameters less than 10 mm. The influence of the used equipment can beseen in FIG. 18 (Heat up behavior of different test specimen). Thereached heating rate of a shouldered test bar (normal induction coil,frequency: 675 kHz) is only half as fast as the equivalent fiber in theinteresting timeframe of the first 3 seconds.

Furthermore, filaments, modified with 30 wt.-% MagSilica VP300, reachthe melting region of PEEK within 0.7 seconds (about 510 K/s). Latestinduction tests with MagSilica HS even shown that heating rates of 720K/s to reach PEEK melting temperature are possible, whereby the use ofthese technologies for nearly all thermoplastic resins is verified.

It will be appreciated that an appropriate process chain is not limitedto the two examples described herein. For example, the number and kindof steps as well as the parameters of the steps could be modified.

The process chains set out and the possible products have at least inparticular embodiments the following advantages individually or incombination:

-   -   The new fixing type of the hybrid yarn facilitates, in        comparison with TFP technology, the damage-free lay-up of        reinforcement fibers also on paths with low radii of curvature        (lay-up radii) and for thick preforms.    -   In comparison with existing tow placement systems, clearly        smaller in-plane lay-up radii without fiber waviness can be        realized.    -   Apart from the very small proportion of ferromagnetic and/or        ferrimagnetic particles, no further auxiliary agents such as low        melting thermoplastic binding agents are required, which can        lead according to the field of use of the material to reducing        hot-wet properties.    -   Material properties can be optimally adapted to the component        loads via the tailor-made orientation of the reinforcement        fibers.    -   Through the high degree of automation of the process chain, a        customer-orientated production in countries with a comparatively        high wage level is possible. Process security is guaranteed.    -   With the production of the preforms on end contour by means of        the tow placement method the cutting of the flat textile product        is avoided. Besides costs for the cutting devices and staff, the        otherwise usual waste is clearly reduced. Quality losses which        are otherwise caused in the form of fiber undulations in the        cutting process and the handling of flexible textiles do not        have to be considered either.    -   The sufficiently high rigidity of the fiber preform facilitates        storage and safe transportation. The production of the preforms        can take place in the textile supplier industry. The workload of        component-unspecific tow placement systems is thus ensured and        the respective expert knowledge of the different branches of the        economy is used.    -   The short cycle times allow the realization of lightweight        construction concepts for a broad field of application. The new        products are thereby characterised by low weight, increased        performance capacity and reduced energy consumption in        operation.

The features of the invention disclosed in the present description, inthe drawings, and in the claims can be essential to implementing theinvention in its various embodiments both individually and in anycombinations. It is contemplated that several modifications can be madeto the embodiments described herein within the spirit and scope of theinvention without departing from the anticipated scope of the claims.

1. A thermoplastic fiber comprising: a core, said core being constructedof a first material; a shell, said shell being positioned to surroundsaid core, said shell being constructed of a second material; andmagnetic particles, said magnetic particles being one of ferromagneticparticles and ferrimagnetic particles, said magnetic particles alsobeing one of mainly arranged in said shell, almost exclusively arrangedin said shell, and exclusively arranged in said shell.
 2. Thethermoplastic fiber of claim 1 wherein said core is round.
 3. Thethermoplastic fiber of claim 1 wherein said shell is round.
 4. Thethermoplastic fiber of claim 1 wherein said first material and saidsecond material are identical.
 5. The thermoplastic fiber of claim 1wherein said first material and said second material are different. 6.The thermoplastic fiber of claim 1 wherein the diameter of individualsaid particles is in a range of about 10 nm to about 20 nm.
 7. Thethermoplastic fiber of claim 1 wherein the diameter of individual saidparticles is about 13 nm.
 8. The thermoplastic fiber of claim 1 furthercomprising: said particles being in agglomerates of particles; and saidagglomerates of particles being in the range of about 100 nm to about200 nm.
 9. The thermoplastic fiber of claim 1 further comprising: saidparticles being in agglomerates of particles; and said agglomerates ofparticles being on the order of about 150 nm.
 10. The thermoplasticfiber of claim 1 wherein said fiber comprises at least one ofpolyetherketone, polyetheretherketone (PEEK), polyphenylene sulphide(PPS), polymide, polyetherimide (PEI), polysulfone (PSU), andpolyethersulfone (PES).
 11. The thermoplastic fiber of claim 1 whereinsaid fiber is unstretched.
 12. The thermoplastic fiber of claim 1wherein said particles are iron oxide modified.
 13. The thermoplasticfiber of claim 1 wherein said core has a diameter, said diameter beingin the range of about 5 μm to about 60 μm.
 14. The thermoplastic fiberof claim 1 wherein said shell has a thickness in a range of about 0.1 μmto about 20 μm.
 15. The thermoplastic fiber of claim 1 wherein aconcentration of said particles in said shell is in a range of about 10weight percent to about 50 weight percent.
 16. The thermoplastic fiberof claim 1 wherein a viscosity thereof is in a range of about 100 toabout 1000 Pa·s.
 17. A hybrid yarn comprising: a plurality ofreinforcement fibers; a plurality of thermoplastic fibers; and at leastsome of the plurality of thermoplastic fibers include at leastproportionately ferromagnetic and/or ferrimagnetic particles.
 18. Thehybrid yarn of claim 17 wherein said yarn is suited for the thermalfixing of fiber preforms for, endless fiber reinforced, fiber compositecomponents, and in particular high performance fiber compositecomponents.
 19. The hybrid yarn of claim 17 wherein at least one of saidferromagnetic particles and said ferrimagnetic particles are in thenanometer range.
 20. The hybrid yarn of claim 17 wherein saidthermoplastic fibers are round.
 21. The hybrid yarn of claim 17, whereinsaid reinforcement fibers are round.
 22. The hybrid yarn of claim 17further comprising: said reinforcement fibers are round; saidthermoplastic fibers respectively include a core, said core having afirst material; and a shell surrounding said core, said shell having asecond material.
 23. The hybrid yarn of claim 17 further comprising:said reinforcement fibers are round; said thermoplastic fibersrespectively include a core, said core having a first material; a shellsurrounding said core, said shell having a second material; and saidfirst material and said second material are identical.
 24. The hybridyarn of claim 17 further comprising: said reinforcement fibers areround; said thermoplastic fibers respectively include a core, said corehaving a first material; a shell surrounding said core, said shellhaving a second material; and said first material and said secondmaterial are different.
 25. The hybrid yarn of claim 17 wherein saidmagnetic particles are one of mainly arranged in said shell, almostexclusively arranged in said shell, and exclusively arranged in theshell.
 26. The hybrid yarn of claim 17 wherein the diameter of saidindividual particles is in a range of about 10 nm to about 20 nm. 26.The hybrid yarn of claim 17 wherein the diameter of said individualparticles is on the order of about 13 nm.
 27. The hybrid yarn of claim17 wherein said particles are in agglomerates of particles, saidagglomerates of particles being in a range of about 100 nm to about 200nm.
 28. The hybrid yarn of claim 17 wherein said particles are inagglomerates of particles, said agglomerates of particles being on theorder of about 150 nm.
 29. The hybrid yarn of claim 17 wherein saidreinforcement fibers include anorganic fibers.
 30. The hybrid yarn ofclaim 29 wherein said reinforcement fibers are at least one of carbon,glass, synthetic polymers, and aramid.
 31. The hybrid yarn of claim 17wherein said thermoplastic fibers include at least one ofpolyetherketone, polyetheretherketone (PEEK), polyphenylene sulphide(PPS), polyimide, particular polyetherimide (PEI), polysulfone (PSU),and polyethersulfone (PES).
 32. The hybrid yarn of claim 17 wherein saidthermoplastic fibers are unstretched.
 33. The hybrid yarn of claim 17wherein said particles are ion oxide modified.
 34. The hybrid yarn ofclaim 17 wherein said reinforcement fibers and said thermoplastic fibersare homogeneously mixed.
 35. The hybrid yarn of claim 17 wherein thediameter of said reinforcement fibers is in a range of about 5 μm toabout 15 μm.
 36. The hybrid yarn of claim 17 wherein the fiber volumecontent of said reinforcement fibers is in a range of about 50 volumepercent to about 70 volume percent.
 37. A fiber preform or semifinishedtextile product comprising: at least one thermoplastic fiber, saidthermoplastic fiber having a core, said core being constructed of afirst material, a shell, said shell being positioned to surround saidcore, said shell being constructed of a second material, and magneticparticles, said magnetic particles being ferromagnetic and/orferrimagnetic particles; and said magnetic particles being one of mainlyarranged in said shell, almost exclusively arranged in said shell, andexclusively arranged in said shell.
 38. A fiber preform or semifinishedtextile product comprising: a hybrid yarn, said hybrid yarn having aplurality of reinforcement fibers, a plurality of thermoplastic fibers;and at least some of said plurality of thermoplastic fibers include atleast one of proportionately ferromagnetic particles and ferrimagneticparticles.
 39. A fiber preform or semifinished textile productcomprising: at least one thermoplastic fiber, said thermoplastic fiberhaving a core, said core being constructed of a first material, a shell,said shell being positioned to surround said core, said shell beingconstructed of a second material, and magnetic particles, said magneticparticles being at least one of ferromagnetic particles andferrimagnetic particles; said magnetic particles being one of mainlyarranged in said shell, almost exclusively arranged in said shell, andexclusively arranged in said shell; a hybrid yarn, said hybrid yarnhaving a plurality of reinforcement fibers, a plurality of thermoplasticfibers; and at least some of said plurality of thermoplastic fibersinclude at least one of proportionately ferromagnetic particles andferrimagnetic particles.
 40. The fiber preform or semifinished textileproduct of claim 39, said fiber preform or semifinished textile productbeing produced by using TFP Technology.
 41. The fiber preform orsemifinished textile product of claim 39, said fiber preform orsemifinished textile product being produced by using Tow PlacementTechnology.
 42. A hybrid yarn comprising: a plurality of reinforcementfibers, a plurality of thermoplastic fibers, at least some of theplurality of thermoplastic fibers including at least one ofproportionately ferromagnetic particles and ferrimagnetic particles; andsaid yarn forming at least one of nonwoven fabric, non-crimp fabric,multiaxial multiply fabric, winding form, woven fabric, knitted fabric,and braided fabric.
 43. A method for producing a fiber preform orsemifinished textile product comprising: providing a hybrid yarn, saidyarn having a plurality of reinforcement fibers, a plurality ofthermoplastic fibers, at least some of the plurality of thermoplasticfibers including at least one of proportionately ferromagnetic particlesand ferrimagnetic particles; and continually adding said hybrid yarnwith simultaneous heating thereof in continuous passing through orpassing by through a magnetic induction heating device or on the sameand subsequent lay-up of said hybrid yarn in any path curve on acarrying layer and fixing of said hybrid yarn by allowing said yarn torigidify.
 44. The method for producing a fiber preform or semifinishedtextile product of claim 43 wherein said carrying layer istwo-dimensional.
 45. The method for producing a fiber preform orsemifinished textile product of claim 43 wherein said fiber preforms arefor endless fiber reinforced, fiber composite components.
 46. The methodfor producing a fiber preform or semifinished textile product of claim43 wherein said fiber preforms are for high performance fiber compositecomponents.
 47. The method for producing a fiber preform or semifinishedtextile product of claim 43 wherein said hybrid yarn is pressed duringor after lay-up on said carrying layer.
 48. A fiber composite componentcomprising: at least one thermoplastic fiber, said thermoplastic fiberhaving a core, said core being constructed of a first material, a shell,said shell being positioned to surround said core, said shell beingconstructed of a second material, and magnetic particles, said magneticparticles being at least one of ferromagnetic particles andferrimagnetic particles, said magnetic particles being one of mainlyarranged in said shell, almost exclusively arranged in said shell, andexclusively arranged in said shell; and a hybrid yarn, said hybrid yarnhaving a plurality of reinforcement fibers, a plurality of saidthermoplastic fibers, and at least some of said plurality ofthermoplastic fibers including at least one of proportionatelyferromagnetic particles and ferrimagnetic particles.
 49. The fibercomposite component of claim 48 wherein the concentration of saidparticles is in a range of about 0.01 volume percent to about 20 volumepercent.
 50. The fiber composite component of claim 48 wherein theconcentration of said particles is in a range of about 0.01 volumepercent to about 2 volume percent.
 51. A fiber composite componentcomprising: at least one thermoplastic fiber, said thermoplastic fiberhaving a core, said core being constructed of a first material, a shell,said shell being positioned to surround said core, said shell beingconstructed of a second material, and magnetic particles, said magneticparticles being at least one of ferromagnetic particles andferrimagnetic particles, said magnetic particles being one of mainlyarranged in said shell, almost exclusively arranged in said shell, andexclusively arranged in said shell; and a fiber preform or semifinishedtextile product, said fiber preform or semifinished textile productproduced by providing a hybrid yarn, said yarn having a plurality ofreinforcement fibers, a plurality of said thermoplastic fibers, at leastsome of said plurality of thermoplastic fibers including at least one ofproportionately ferromagnetic particles and ferrimagnetic particles, andcontinually adding said hybrid yarn with simultaneous heating thereof incontinuous passing through or passing by through a magnetic inductionheating device or on the same and subsequent lay-up of said hybrid yarnin any path curve on a carrying layer and fixing of said hybrid yarn byallowing said yarn to rigidify.
 52. The fiber composite component ofclaim 51 wherein the concentration of said particles is in a range ofabout 0.01 volume percent to about 20 volume percent.
 53. The fibercomposite component of claim 51 wherein the concentration of saidparticles is in a range of about 0.01 volume percent to about 2 volumepercent.
 54. A fiber composite component comprising: a hybrid yarn, saidhybrid yarn having a plurality of reinforcement fibers, a plurality ofthermoplastic fibers, and at least some of said plurality ofthermoplastic fibers including at least one of proportionatelyferromagnetic particles and ferrimagnetic particles; and a fiber preformor semifinished textile product, said fiber preform or semifinishedtextile product produced by providing said hybrid yarn and continuallyadding said hybrid yarn with simultaneous heating thereof in continuouspassing through or passing by through a magnetic induction heatingdevice or on the same and subsequent lay-up of said hybrid yarn in anypath curve on a carrying layer and fixing of said hybrid yarn byallowing said yarn to rigidify.
 55. The fiber composite component ofclaim 54 wherein the concentration of said particles is in a range ofabout 0.01 volume percent to about 20 volume percent.
 56. The fibercomposite component of claim 54 wherein the concentration of saidparticles is in a range of about 0.01 volume percent to about 2 volumepercent.
 57. A fiber composite component comprising: at least onethermoplastic fiber, said thermoplastic fiber having a core, said corebeing constructed of a first material, a shell, said shell beingpositioned to surround said core, said shell being constructed of asecond material; and magnetic particles, said magnetic particles beingat least one of ferromagnetic particles and ferrimagnetic particles,said magnetic particles being one of mainly arranged in said shell,almost exclusively arranged in said shell, and exclusively arranged insaid shell; a hybrid yarn, said hybrid yarn having a plurality ofreinforcement fibers, a plurality of said thermoplastic fibers, and atleast some of said plurality of thermoplastic fibers including at leastone of proportionately ferromagnetic particles and ferrimagneticparticles; and a fiber preform or semifinished textile product, saidfiber preform or semifinished textile product produced by providing saidhybrid yarn and continually adding said hybrid yarn with simultaneousheating thereof in continuous passing through or passing by through amagnetic induction heating device or on the same and subsequent lay-upof said hybrid yarn in any path curve on a carrying layer and fixing ofsaid hybrid yarn by allowing said yarn to rigidify.
 58. The fibercomposite component of claim 57 wherein the concentration of saidparticles is in a range of about 0.01 volume percent to about 20 volumepercent.
 59. The fiber composite component of claim 57 wherein theconcentration of said particles is in a range of about 0.01 volumepercent to about 2 volume percent.
 60. A method for producing fibercomposite components comprising: providing the continuous addition of ahybrid yarn, said hybrid yarn having a plurality of reinforcementfibers, a plurality of thermoplastic fibers, and at least some of saidplurality of thermoplastic fibers including at least one ofproportionately ferromagnetic particles and proportionatelyferrimagnetic particles; simultaneous heating thereof in continuouspassing through or passing by through a magnetic induction heatingdevice or on the same and subsequent lay-up of said hybrid yarn in anypath curve on a carrying layer and fixing of the hybrid yarn by allowingit to rigidify; and thermoforming of the fiber preform produced for theproduction of a three-dimensionally formed fiber composite component.61. The method for producing fiber composite components of claim 61wherein said components are endless fiber reinforced, fiber compositecomponents.
 62. The method for producing fiber composite components ofclaim 61 wherein said components are high performance compositecomponents.
 63. The method for producing fiber composite components ofclaim 61 wherein said carrying layer is two-dimensional.